The present disclosure relates to a simplified fusing system. More particularly, the present disclosure relates to a fusing system in which several of the components typically associated with the fusing system need not be replaced along with fusing system rollers.
Electrophotographic printing and copying devices typically are provided with fusing systems that serve to thermally fuse a toner image onto a recording medium, such as a sheet of paper. Such fusing systems normally comprise a heated fuser roller and a heated pressure roller that presses against the fuser roller to form a nip in which the fusing occurs. FIG. 1 illustrates a simplified end view of a typical prior art fusing system 100. As indicated in FIG. 1, the fusing system 100 generally comprises a fuser roller 102, a pressure roller 104, internal heating elements 106, and a temperature sensor 108. The fuser and pressure rollers 102 and 104 comprise hollow tubes 110 and 112 that are coated with outer layers 114 and 116 of elastomeric material.
The internal heating elements 106 typically comprise halogen lamps that uniformly irradiate the inner surfaces of the rollers 102 and 104. Through this irradiation, the inner surfaces are heated and this heat diffuses to the outer surfaces of the fuser and pressure rollers 102 and 104 until they reach a temperature sufficient to melt the toner (e.g., approximately between 160xc2x0 C. to 190xc2x0 C.). The fuser roller and the pressure rollers 102 and 104 rotate in opposite directions and are urged together so as to form a nip 118 that compresses the outer layers 114 and 116 of the rollers together. The compression of these layers increases the width of the nip 118, which increases the time that the recording medium resides in the nip. The longer the dwell time in the nip 118, the larger the total energy that the toner and recording medium can absorb to melt the toner. Within the nip 118, the toner is melted and fused to the medium by the pressure exerted on it by the two rollers 102 and 104. After the toner has been fused, the recording medium is typically forwarded to a discharge roller (not shown) that conveys the medium to a discharge tray.
Normally, fusing systems such as that depicted in FIG. 1 are periodically replaced because of degradation of the outer layers of the fuser and pressure rollers. This degradation normally occurs due to the high temperatures to which the fuser and pressure rollers are exposed during use. In particular, the outer layers tend to delaminate over time due to these temperatures. In that the internal heating elements comprise integral parts of the fuser and pressure rollers, these elements are normally discarded along with the rollers. In addition, the temperature sensors and electrical connectors associated with the rollers and/or the internal heating elements are also discarded.
Discarding of the internal heating elements and the other components identified above is disadvantageous for several reasons. First, these components are relatively expensive and therefore significantly increase (e.g., approximately double) the cost of the replacement fusing system. In that such replacement typically occurs several (e.g., four or more) times over the life of the imaging device, these costs are multiplied. Second, the required replacement of these components is wasteful in that they typically fail much less frequently that the fuser and pressure rollers. Indeed, if they were not part of the fusing system, the internal heating elements, temperature sensors, and associated electrical connectors would most likely last as long as the imaging device without replacement.
From the foregoing, it can be appreciated that it would be desirable to have a simplified fusing system such that fewer components are discarded when the fuser and pressure rollers of the fusing system are replaced.
The present disclosure relates to a fusing system for fusing toner to a recording medium. The fusing system comprises a fuser roller that does not have an internal heat source, a pressure roller that does not have an internal heat source, the pressure roller being in contact with the fuser roller, and an external heat source that heats at least one of the fuser and pressure rollers.
In addition, the present disclosure relates to a method for heating in a fusing system. The method comprises the steps of providing a fuser roller and a pressure roller that do not have internal heat sources, providing an external heating source that is associated with at least one of the fuser and pressure rollers, and heating the at least one of the fuser and pressure rollers with the external heating source.
The present disclosure further relates to a method for replacing a fusing system of an imaging device. The method comprises the steps of removing a fuser roller of the fusing system from the imaging device, removing a pressure roller of the fusing system from the imaging device, leaving all heat sources of the fusing system in place within the imaging device, inserting a new fuser roller into the fusing system, and inserting a new pressure roller into the fusing system.
The features and advantages of the invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.